Hi, all
I'm about to dowel for the first time...I'm using 3/8" mahogany dowels. Assuming the dowels are to specs, do I use the same size drill bit or slightly oversized? If so, by how much? The dowels will be glued.

Thanks for your advice!
R

TomRobb

07-12-2001, 01:01 PM

Dowels for what? What are you making? What function are the dowels to serve?
I wouldn't assume the dowels are exactly any particular size.

Roger Stouff

07-12-2001, 04:45 PM

Hi, Tom
In general, interior joinery on a boat I'm getting ready to start (my second) by themselves and as covers for screw countersink holes.

I probably confused matters by saying "if the dowels are to specs" but what I mean was, if I definitely have a 3/8 dowel, should the hole be exactly 3/8 or, say, 1/64 over?

This is my first experience with dowels, believe it or not, after years of wood working and other types of joinery.

Thanks!

RStouff

Ed Harrow

07-12-2001, 05:11 PM

Hmmmm, if I understand you correctly, you are going to countersink some screws and then bung the holes to cover the screws. If that is indeed what you are doing, then you want to go to Jamestown, or Lee Valley, or some place like that and get matched countersinks and plug cutters.

Dowels, per se, are not used to plug holes over screw heads.

Bob Cleek

07-12-2001, 08:24 PM

Yea, definitely, what Ed said. Go to any of the catalogs or to a decent hardware store and get yourself a collection of Fuller tapered bits, stop collars and countersink sleeves, plus the matching plug cutters. You can buy them in tidy sets, but you end up paying more because you only need a couple different sized stop collars and countersinks which will fit the whole range of tapered bits. Cheaper to buy what you need, since a whole bit-collar-sink set up runs around fifteen or twenty bucks last time I checked. The plug cutter, which should run about eight bucks, will pay for itself in short order, since you can make up unlimited numbers of bungs (plugs) in your drill press out of the scrap you have on hand instead of paying .08 each for them!

Keep in mind that bungs (plugs over countersunk screws) are cut out of face grain wood (generally) matching the grain they go into. (You aren't going to screw into the endgrain, but if you had to bung endgrain, then the plug should match that as well.) They are a tight fit and only need a bit of varnish, shellac or glue to hold them in. Dowels as fasteners, on the other hand, (which are called treenails, in sailor talk, pronounced "trunnels") are for fastening and should be turned with the grain running their length for reasons that should be obvious. Bungs, by the way, are always set with their grain running the same direction as the grain on the face piece into which they are set, never across the grain.

Mike Field

07-12-2001, 10:07 PM

What Ed and Bob said about bungs (except that we call them "plugs.") The basic point at issue is grain direction, and a subsidiary one is timber-matching.

HOWEVER, it's quite okay to use dowels as such to join pieces of timber in internal joinery, which I think was part of your question. I myself would use hardwood dowels for this purpose for strength reasons. What sort of mahogany are these dowels made from?

Also, are they plain or ribbed? (Ribbed have little longitudinal channels scored in them all around the periphery.) Ribbed are much better than plain, as they don't trap air in the hole ahead of them as you drive them (the pressure of which could force them back out a bit again,) and they also allow the glue to form a good keyed lock.

If you can only get plain ones, then I think it's worthwhile sawing at least one longitudinal groove in each of them for pressure-relief purposes.

If you're using ribbed ones, then I'd try drilling an experimental hole one size smaller than the dowel diameter first, using a scrap piece of the same parent timber. The timber in the ridges of the dowel should compress a bit as you drive it, giving a good snug fit. However, if the fit is really too tight, just go up one size of drill.

Some people might tell you otherwise here, but I think it's okay to use PVA adhesive on internal joinery. It's not waterproof, though, so you need to think a bit about where you're using it, first.

As an aside, have you thought about splitting your own dowels? Split are always potentially stronger than milled, because the grain always run longitudinally. It's a somewhat time-consuming business to make them, though, because to round it off you need to drive each one as you make it through a hole in a metal die, and you also need to make the die first.

Finally, going back to plugs for a minute, you wouldn't normally glue plugs in at all -- just give them a wipe with paint or varnish as you insert them. Then you can get them out again without too much trouble if you ever need to refasten, and you can do it without damaging the face timber.

Hope this help. Mike.

[This message has been edited by Mike Field (edited 07-12-2001).]

Wayne Jeffers

07-12-2001, 10:56 PM

To add to what Mike said -- If you buy the ribbed dowels to use for blind doweling, you use the same size bit, e.g., for a 3/8 inch dowel, you should use a 3/8 inch brad point bit. The result will be a very tight fit. Drill each hole a little deeper than 1/2 the dowel's length, otherwise you may not be able to get the two pieces you're joining to come completely together.

For internal joinery (or furniture), the yellow aliphatic (sp?) wood glue, such as Titebond, are inexpensive, easy to use, and well-suited for gluing dowels. They clean up with water, and they are water-resistant (but not water-proof) after drying.

Wayne

Roger Stouff

07-13-2001, 09:36 AM

Thanks everyone for your replies.

I know my questions was kinda vague, 'cuz I'm fight a summer flu!

Having used mortise and tenons, box-joints and dovetails for years, I got to thinking on dowels just recently. To try to clarify again (through the Dayquil haze) I want to use some doweling for interior joinery with contrasting colors. Mahogany (honduras is what I have) on cypress (the best local boat wood available in the south!) for visual appeal, but of course I want them to be strong, too, which prompted the question. The dowels I have are not ribbed, but I see that it would be simple enough to add them. In the future, that's what I'll order.

I have built one 12' bateau of my father's design, which came out great. I'm embarking on a 16' model which I want to dress-up more. But I'm typically a furniture kinda woodworker, so I'm learning!

Again, thanks for your help, and you'll probably hear more from me ... hopefully in a more lucid state.

Bruce Hooke

07-13-2001, 09:47 AM

I just want to emphasize one point touched on by some of the other replies -- for both dowel joinery and bungs, twist drill bits generally drill too sloppy a hole to be suitable for accurate and good looking work. This is especially true of bungs, where the fit will be highly visible if the area is being varnished and where the staying power of the bung to some degree depends on how well it fits the hole. Use either brad point or Forstner bits. One implication of this is that, since brad point and Forstner bits come in fractional sizes you pretty much have to fit the dowel or bung to the bit rather than the other way around because the bits jump too much in size for 'going up one size' to be of much use. If the reasons given by the previous post are not enough to convince you not use dowels for bungs, the final straw is that dowels are generally not round enough and not sized accurately enough to work well as bungs, especially in light of the drill bit issue I just mentioned.

Finally, if the dowel is not ribbed I would say that cutting a good grove is essential. Skipping this step is a good way to split your stock as you try to force the dowel in against the pressure of the glue and there is no other way for the pressure to release. Assuming this is for interior joinery (and that is the only place where you should use dowel joinery) you may just want to switch to the standard short ribbed dowels even though they are not of a rot resistant material, since they come pre-ribbed and rot should not be an issue for interior work anyway.

Bob Cleek

07-13-2001, 08:46 PM

I tried the ribbed ones once and the hole didn't seem any tighter. I couldn't detect any difference between ribbed and regular. Maybe its different with regular and small sizes. I was using Jumbo ribbed ones.

Mike Keers

07-13-2001, 09:14 PM

Of course if you can't find ribbed ones, you can always plane a flat on one side with a block plane....Cleek might not sit still for that tho! http://media5.hypernet.com/~dick/ubb/eek.gif

[This message has been edited by Mike Keers (edited 07-13-2001).]

Ed Harrow

07-13-2001, 09:16 PM

Oh Bob, what are we going to do with you http://media5.hypernet.com/~dick/ubb/rolleyes.gif

abe

03-17-2004, 09:22 AM

Thanks for finding this and the plug cutter topics, Jim Hillman. Some good pointers for the apprentice as well as some "Classic Cleek" thrown in.

I estimate that the 36 ash bungs I need for the Rangeley rub rails to be cut today will cost $2.00 each. In order to recover my capital outlay for a Leigh Valley tapered drill/bung cutter kit, 1800 bungs will be required over my lifetime...........I suppose a large hull would require a few thousand.

abe

Dave R

03-17-2004, 11:37 AM

Roger, if you are pinning pieces together with dowels and want ribs, you can make the ribs as needed with a pair of slip joint pliers. Just clamp down on the dowel with the serrated part of the jaws.

I'm not certain, but Cleek might use that method for putting ribs on his. ;)

As far as fit, I suspect you're best bet it to drill some holes and see how they work. My experience with dowels is that there aren't really round but slightly elliptical due to shrinkage after milling.

Nicholas Carey

03-17-2004, 03:53 PM

Originally posted by RStouff:
&hellip;I got to thinking on dowels just recently&hellip;I want to use some doweling for interior joinery with contrasting colors.I just saw Miller Dowels (http://www.millerdowel.com/) in action and it looks like an interesting system for joinery:

You fellers did notice the date Roger asked his question, no? I reckon we haven't heard from him might be because he's out on the lake somewhere in that boat fishing.

JayBoat95

03-18-2004, 09:14 AM

This is odd. Not only is this thread years old, but I find it insulting to suggest that one has to buy special "jamestown matching cutter and countersink". Do what everyother woodworker does......go to Home Depot and buy a $8 plug cutter and buy a $6 countersink that fits your 3/8" drill. Open the package and make sure the countersink fits the plug cutter snugly. If not, if they rattle, then exchange them for propper fitting ones.

Wild Dingo

06-21-2004, 04:53 AM

I think your right about Roger Norm havent seen or heard from him in a long time... fishin must be good down there in Looeesiana :cool:

Anyway Im glad this thread popped up... cause just recently Ive found myself in need of dowels be am either too much of a tightwad or just to lazy to bother going down the road to buy some so Ive been muckin about making them

Using Jarrah and Tuart... the Jarrah are better Sheoak doesnt seem to like the idea while the tuart bluntens my block plane far to fast! :rolleyes:

So heres a wee question Ive been thunkin on as Im planing these things round... oh for the grooves? I just score down the length in three places with the chizel nice clean groove :cool: so my question...

Treenails... or rather trunnels... how are they made? are they round same as the dowels or are they more squarish in shape? do they taper and what sort of taper are we talking about? Im quite curious as Im spending a bit of time pondering methods and madness with boatbuilding and furniture making Yaz wants a chyristal cabinet for her 21st in a few months and Im damned if I want to spoil it with metal screws and such other than the bronze or brass hinges and door handles... so anyway does anyone have any info on the treenails?

Thanks fellas :cool:

paladin

06-21-2004, 06:41 AM

Shane..
Ya gotta have a trunnel tree. I gots three or four planted out in the back yard where Critter does her thing. They izz special as I had to import them. They izz jenn-yu-wine boat trunnels 'cause it izz a botetrunneltreee. The larger trunnels grow close to the ground and they gitts smallare as they grows closer to the top. They izz reel Osage Orange trunnels too.......

Wooden Boat Fittings

06-21-2004, 07:21 AM

.
Thank you, Mr Chucknut. :D :D :D

Forget the plane, Shane. Get a bit of 1/4" steel plate and drill it to the diameter you want the trennels to be. Cut (which is to say, split) each one roughly, but oversize, then pound it through the hole in your new steel die.

They're not tapered (normally, at least,) but the ends are slotted and after insertion a small wedge is driven into the slot to tighten all up.

Mike
.

Bob Smalser

06-21-2004, 09:07 AM

Originally posted by Wooden Boat Fittings:
.
Forget the plane, Shane. Get a bit of 1/4" steel plate and drill it to the diameter you want the trennels to be. Cut (which is to say, split) each one roughly, but oversize, then pound it through the hole in your new steel die.

They're not tapered (normally, at least,) but the ends are slotted and after insertion a small wedge is driven into the slot to tighten all up.

Mike
.I suspect simple, slotted dowels glued in and the wedge driven in across the grain are just as strong as Miller's gizmo. I've certainly used a lot of them still in service after 3 decades.

And the JR Beall Tool company makes all manner of sizing plates used with their wood threader jig.